The present invention relates generally to construction materials and techniques and more particularly to windstrip bracing for frame structures such as stud walls and the like.
In the construction of buildings and other structures, exterior and interior walls are commonly provided by first erecting a wall frame structure comprising top and bottom plates between which are fastened spaced, upright nominal size two inch by four inch wooden studs and by then attaching the exterior or interior wall covering, such as dry wall or siding, to the studs. One problem associated with such construction is "racking", the term used to describe the lateral movement or the shifting of the top or bottom plate with respect to the other plate. Racking may occur in wooden structures due to wind or seismic load forces on the wall causing the top plate, for example, to shift laterally with respect to the bottom plate such that the studs correspondly shift and the wall frame loses its desired squaredoff, rectangular configuration.
It has therefore become common practice to nail, or otherwise fasten, a nominal size 1 inch by 4 inch wooden brace to the studding such that the brace extends downwardly from the top plate in a diagonal direction across several of the adjacent studs to the bottom plate of the wall frame structure. This added bracing substantially eliminates racking, but the addition of the brace poses another problem. The exterior siding or the dry wall, as the case may be, cannot then be nailed to the studs without notching portions of the studding and fitting the brace into the cut away portions. This, of course, adds greatly to the time required to erect the stud wall and contributes to a substantial rise in the cost of construction. Accordingly, it is desirable to provide a brace which, when installed, is substantially flat with respect to the surface of the stud wall, but which is also strong enough to prevent racking.
One such brace is described in U.S. Pat. No. 4,016,698, issued to D. Rogers wherein the wooden brace is replaced by a flat metal strap having a plurality of of preformed holes through which nails can be driven to attach the strap to the stud wall at various points on the diagonal.
A similar brace is described in U.S. Pat. No. 3,591,997, issued to J. Tennison, Jr., et al. As described therein, the edge flanges of a sheet metal channel member are accommodated in a pair of spaced, generally parallel saw kerfs extending diagonally across the stud wall from the top plate to the bottom plate. The channel member has multiple openings arranged in a pattern which insures that several of such openings are in alignment with each portion of the frame that the brace crosses thereby permitting the use of multiple fasteners to connect the brace to each stud as well as to the upper and lower plates of the frame.
Still another brace, or metal support strip, is disclosed in U.S. Pat. No. 3,875,719, issued to D. Menge wherein the brace comprises a generally T-shaped metal strip having a generally U-shaped portion forming the base leg of the T. When installed, the U-shaped portion is positioned in a saw kerf extending transversely across studs, trusses, joists, or the like. The strip is fastened, and the U-shaped portion is spread outwardly, by driving a nail downwardly inside the U-shaped portion through the bottom of the strip and into the structural element. Although some positive holding action for securing the brace in the transverse channel is provided by the expansion of the bottom of the U-shaped portion where the nail expands the metal outward into the wood, any positive holding action obtained thereby is believed to be minimal because the sides of the base leg at the bottom end of the U-shaped portion are joined by the U-shaped portion and thus expansion of the base leg near the bottom of the U-shaped portion is thought to be minimal. Indeed, it is believed that the lateral forces applied by the nail to the top of the U-shaped portion where it meets the top edge of the transverse channel may induce the nail or other fastener to pull from the wood with the result that the brace may become loose in the channel and weaken the structure.